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The Safety of Low-Molecular-Weight Heparin During and After Pregnancy

Lu, Eric MD*; Shatzel, Joseph J. MD; Salati, Jennifer MD; DeLoughery, Thomas G. MD§

Obstetrical & Gynecological Survey: December 2017 - Volume 72 - Issue 12 - p 721–729
doi: 10.1097/OGX.0000000000000505

Importance In industrialized countries, venous thromboembolism remains a leading cause of mortality in pregnant women. Low-molecular-weight heparin (LMWH) is the most commonly recommended anticoagulant in pregnancy, having been proven effective and safe in multiple prospective clinical trials.

Objective The aim of this article is to outline existing recommendations for proper use of LMWH in pregnancy and data on risks of LMWH.

Evidence Acquisition We reviewed guidelines from a number of professional societies. We also examined the current literature behind the various risks associated with LMWH use.

Results and Conclusions Our review outlines the current data that guide the use of LMWH in pregnancy. With prophylactic dosing, LMWH comes with a 0.5% risk of antepartum bleeding and a 1% risk of postpartum hemorrhage that is not different from clinical trial controls. With treatment dosing, there is a 1.5% risk of antepartum bleeding and a 2% risk of postpartum hemorrhage. Overall, current evidence behind these risks is limited, and this review suggests areas of further study moving forward.

Target Audience Obstetricians and gynecologists, family physicians.

Learning Objectives After completing this activity, the learner should be better able to define the specific risk factors and preexisting conditions that would warrant LMWH use in pregnancy and postpartum; describe the different available doses of LMWH, when to use each dose, and when monitoring is appropriate; and discuss the risks of anticoagulation with LMWH during various stages of pregnancy and birth.

*Internal Medicine Resident, Department of Medicine, †Hematology and Medical Oncology Fellow, Division of Hematology/Oncology, Knight Cancer Institute, ‡Assistant Professor of Obstetrics & Gynecology, Division of Maternal Fetal Medicine, and §Professor, Division of Hematology/Oncology, Knight Cancer Institute, Oregon Health & Science University, Portland, OR

All authors, faculty, and staff in a position to control the content of this CME activity and their spouses/life partners (if any) have disclosed that they have no financial relationships with, or financial interests in, any commercial organizations pertaining to this education activity.

T.G.D. has disclosed that the US Food and Drug Administration has not approved the use of enoxaparin for the treatment of pregnant women with mechanical prosthetic heart valves as discussed in this article. Please consult the product's labeling for approved information.

This manuscript has not been presented or submitted elsewhere.

Correspondence requests to: Eric Lu, MD, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239. E-mail:

Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.